1. Field of the Invention
This invention relates to a technology of treating the surface of a rotatable disc such as a magnetic disc to be used as a storage medium of a computer.
2. Related Art Statement
A magnetic disc to be used as a storage medium of a computer is typically produced by boring a through hole at the center of a disc made of an aluminum alloy or the like to make it show predetermined inner and outer diameters and then subjecting it to a sequence of surface treatment steps. The surface treatment steps include a grinding step for grinding the surface by means of a grinding wheel, a lapping step using a lapping agent containing abrasive grains of alumina, silicon carbide, diamond or the like, a polishing step using a polishing agent containing grains finer than those of the lapping agent, a sputtering step for forming a magnetic film on the surface, a plating step, a cleaning step and a visual inspection step.
In the course of forming a magnetic film, the magnetic disc is subjected to a texturing operation for improving the orientation of the magnetic film, where fine streaks are produced on the mirror polished surface of the disc to make it slightly coarse.
Various surface treatment apparatus have been proposed to treat the surface of a disc in various different ways such as cleaning the surface. Many of them comprise a treatment roller, the outer peripheral surface of which is pressed against the surface of the disc to be treated and slidingly moved relative to the disc. Japanese Patent Publication No. 7-14509 discloses an apparatus for cleaning a disc.
With any known surface treatment apparatus of the above described type, a support roller for supporting the disc is driven to rotate by means of a drive source, thereby driving the disc to rotate. On the other hand, a brush-like member for cleaning the surface of the disc is driven by means of another drive source to slidingly move on the surface of the disc. Thus, known surface treatment apparatus comprise two drive sources, one for driving the disc and the other for driving the brush to inevitably make the apparatus rather complex.